Apparatus and process for atomizing liquids,particularly carbon black raw materials

ABSTRACT

There is provided an apparatus for atomizing a liquid by means of a gas comprising a nozzle at one end, a jacket pipe for gas contracting at said one end, a feed pipe for liquid arranged axially inside said jacket pipe and terminating therein as a constricted end, the length of both pipe ends in the axial direction being at most 10 times the inner diameter of the jacket tube. The apparatus is preferably used in the production of furnace blacks wherein the liquid hydrocarbon raw material is introduced into an atomizing stream of higher velocity and the dispersion is then separated into a reaction chamber.

United States Patent Kiihner et al.

APPARATUS AND PROCESS FOR 7 ATOMIZING LIQUIDS, PARTICULARLY CARBON BLACKRAW MATERIALS Inventors: Gerhard Kiihner; Heinrich Sauer; Gerhard Jager,all of Grossauheim;

r ard, Pu ngnwe fsa g r s 1 Hanan, all of Germany Deutsche GoldundSilber-Scheldeanstalt vormals Roeasler, Frankfu (Main), Germany Filed:May 26, 1971 Appl. No.: 147,248

Related u.s. Application om Continuation of Ser. No. 801,554, Feb. 24,1969, abandonedJ Assignee:

Foreign Application Priority Data Feb. 22, 1968 Germany ..P 16 25 206.5

U.S. Cl. ..239/420, 239/422, 239/424 Int. Cl......F23d 11/16, F23d13/40, F23d 15/00 Field of Search ..239/418, 420 0, 424 X, 422 X,239/4345 References Cited UNITED STATES PATENTS Heysel .239/420 x Oct.31, 1972 1,279,315 7 Foerst ..239/424 1,398,397 11/1921 Ryder et a1...239/424 1,989,696 2/1935 I Kelley; ..239/424 2,532,851 12/ 1950Meyer.....'. ..'239/420 X 2,600,040 6/1952 Widmayer ..239/434.5 X2,808,294 10/1957 Tamminga ..239/424 X 3,112,882 12/1963 Gilbert..239/422 FOREIGN PATENTS OR APPLICATIONS 273,511 4/1914 Germany........239/420 Primary Examiner-Lloyd L. King Attorney-Cushman, Darby &Cushman [57] ABSTRACT There is provided an apparatus for atomizing aliquid by means of a gas comprising a nozzle at one end, a jacket pipefor gas contracting at said one end, a feed pipe-for liquid arrangedaxially inside said jacket pipe and terminating therein as a constrictedend, the

length of both pipe ends in the axial direction being at most 10 timesthe inner diameter of the jacket tube. The apparatus is preferably usedin the production of furnace blacks wherein the liquid hydrocarbon rawmaterial is introduced into an atomizing stream of higher velocity andthe dispersion is then separated into a reaction chamber.

7 Claim, 2 Drawing Figures v the reaction space, which must be plant forthe production of furnace black and a feasible process for theproduction of furnace black with improved properties.

.In the furnace black process a liquid hydrocarbon as the carbon blackforming raw material isthermally decomposed or incompletely burned in a'reaction chamber which, for example, is held atthe necessarytemperature by burning a fuel gas. Several apparatus are known for thesupply of the liquid raw material into effective spraying.

A known design of such a burner consists of a central tube through whichthe liquid raw material flows and which is surrounded by a coaxialjacket pipethrough which is introduced an atomizing gas. Both tubes arepractically cylindrical and end in the same plane so that a free liquidjet is formed which becomes dispersed in droplets in front of thecentral pipe by the gas (the socalled support gas) flowing with constantvelocity from the jacket tube.

According to another known design atomizing gas and liquid raw materialenter through one or more openings in the reaction chamber after theyhave been mixed at a considerable distance away from the openings. Sincethe mixture must travel a long way from the mixing place to the exitthere occurs in the feed pipe a segregation of the components whichleads extensively to the formation of an adhering liquid film on thewalls of the pipe while the gas preferably in the center of the pipeclears a flow channel and the liquid is removed from the walls anddispersed onlyat the end of the pipe.

By means of both of these burnerconstructions only the customary furnaceblacks with a surface area below about 150 m lg can be economicallyproduced. The production of blacks with higher specific surfaceareaswould require substantially increased amounts of combustion air wherebythe yield of blacks is very greatly reduced. For these reasons until nowblacks with a specific surface area of more than about 150 m /g have notbeen produced on a technical scale in furnace devices.

It has now been found unexpectedly that blacks of very high specificsurface area can be produced in good yields in furnace black devices,such blacks being useful as color blacks, if an apparatus according toapplicants invention is used for atomizing of the liquid feedstock.Moreover, for blacks which are used for the reinforcing of rubberobvious advantages in the form of an increased structure and anessentially improved abrasion behavior are obtained.

The apparatus of the invention is characterized in that there isprovided a jacket tube with a nomle at one end, narrowing in thevicinity of the nozzle and a feed pipe for the liquid arranged withinthe jacket pipe and ending therein whereby the distance between bothpipe ends in the axial direction is a maximum of times the internaldiameter of the jacket pipe. The minimum done with quick and distancebetween the pipe ends is 0.1 times the internal diameter of the jacketpipe. I

Appropriately the feed pipe for the liquid is movable along thelongitudinal axis relative to the jacket pipe.

In a preferred form of the apparatus of the invention the feed pipe forthe liquid ends in the tapering part of the jacket pipe near the nozzle.

Preferably the nozzle of the jacket has an orifice of a smaller diameterthan the jacket pipe itself.

The noule can also have either a cylindrical shape or I the shape of aventuri or laval nozzle.

The liquid raw material leaving the feed pipe, preferably underpressure, is dispersed into fine droplets by the bypassing gas of highvelocity still within the jacket pipe. An especially intensivedispersion is achieved if the feed pipe is placed so that its orifice isin the region of the contraction of the jacket pipe, if necessaryoutside its central axis.

The velocity of the gas stream increases progressively with decreasingcross sectional area of the jacket pipe which improves the dispersion ofthe droplets of liquid. I The formed air-oil-mist is further acceleratedby the nozzle at the end of the jacket pipe. This effect is especiallystrong if the nozzle is shaped as a venturi tube or a laval nozzle. Sothe mixture is transferred thereby with extraordinarily high velocityand turbulence into the reaction chamber. The entrance velocity and thespraying angle can be influenced by the choice of the nozzle diameterand the nozzle shape.

The technical advantage over the first of the previously described knownburner designs arises from the acceleration of the gas-liquid-dispersionafter the dispersion process.

The advantage in comparison with the second of the known burnerconstructions is that no oil film can adhere to the nozzle wall.

An additional advantage of workingwith a carbon black furnace equippedwith the spraying apparatus of the invention over the known methods isthat air can be used as an atomizing gas without difficulties, withoutdanger that this air operates as a harmful component in the reactionmixture affecting yield and carbon black I properties. It has been foundunexpectedly that in contrast to the experiences made with conventionalburners the amount of the atomizing air can be increased at the expenseof the so-called combustion air otherwise added to the reaction chamberand supporting the heating flame in the furnace. Thereupon there isattained an increase in the specific surface area of the carbon blackformed without loss of yield.

The apparatus of the invention creates the possibility of producing highactivity color black in customary furnace black equipment with goodyields without great construction changes to the furnace itself beingnecessary. Concerning rubber blacks there is obtained improved qualitywhich especially concerns the structure and abrasion behavior. Of courseall of the customary additional apparatus employed with customaryburners can be used with the burner of the invention in so far as theyconcern the supply of a combustion gas. For example, a second outerjacket pipe can be used.

Accordingly, by use of the apparatus of the invention there is developeda process for the production of furnace color black of high surface areaand high yield, by

spraying into a gas stream of higher velocity, preferably under pressurea liquid hydrocarbon serving as raw material and dispersing these,whereby the resulting dispersion is first accelerated, and then sprayedinto the reaction chamber.

The invention is furthermore directed to a process for the production offurnace black in good yields for incorperation into rubber achievingthereby high structure and also improved abrasion properties. Theprocess comprises spraying into a gas stream of high velocity,preferably under pressure, a liquid feedstock and dispersing this,whereby the resulting dispersion is first accelerated, and then sprayedinto the reaction chamber.

According to an especially preferred form of the process of theinvention the hydrocarbon is introduced into the gas stream being in thestate of the acceleration.

One can use air for the dispersion without the disadvantage with regardto the yield of the carbon black and its properties.

The invention will be understood best in connection with the drawingswherein.

FIG. 1 is a vertical elevation partly broken away in section of theapparatus; and

FIG. 2 is a sectional view taken along the line 2--2 of FIG. 1.

Referring more specifically to FIG. 1 of the drawings the apparatusconsists essentially of a liquid feed pipe 12 which at its orifice has aconstriction 5 by which the exit velocity of the liquid becomesdetermined. This oil feed pipe enters in the back part of the apparatusin the jacket pipe 6 and 11 fixed for the gas feed and runs along thelatters middle axis through the centrally disposed clearance support 7to the cylindrical bore hole of the nozzle 1.

The pipe 12 is bound fimily to the pipe 11 which forms the backcontinuation of the pipe 6 and can be moved with the help of the nut 9and the distance ring 10 in the direction of the burner axis. Themovability of pipes 12 and 11 relative to pipe 6 allows a regulation ofthe dispersing action inside pipe 6.

The atomizing gas enters through the nipple 13 in the jacket pipe 11 andgets into the space between the jacket pipe and the oil feed pipe in theforward part of the apparatus. At this point the jacket pipe 6 contractsas shown at 4, in which contraction the gas undergoes an acceleration.In the region of this contraction the liquid carbon black forming rawmaterial comes out of the oil pipe 5 as shown in the drawing and becomesdispersed in the accelerating gas stream and finally leaves with highvelocity from the nozzle 1 as a homogeneous atomized mixture. In placeof the nozzle 1 there can be used other forms of nozzles such as venturior laval nozzles which are examples of convergingdiverging type nozzles.

The jacket pipe 6 has an inner diameter of 10 mm. for its major lengthand terminates in a contracting end 4 having a length in the axialdirection of 12 mm and an inner diameter at its small end adjacent thenozzle of 3.5 mm. The feed pipe 12 has an inner diameter of 4 mm whichwas reduced to 2 mm at its constricted end 5.. The end 5 has a length inthe axial direction of 23 mm. The nozzle 1 has a orifice of 3.5 mm.

Of course it will be understood that the above given dimensions shallnot limit the burner of invention dimensionally. The given dimensionsrather represent one possible relationship between the constructionparts of the burner. Test series have shown that the burner of inventioncan be enlarged without limitation to sizes which correlate with anygiven furnace without loosing its efficiency.

In the illustrated form of the apparatus for carrying out the inventionthe jacket pipe is surrounded by an outer jacket pipe 8 for theintroduction of combustion gas. The combustion gas enters the apparatusat point 14 and leaves this through radially arranged bore hole 3 (FIG.2).

The invention will be further explained by the following examples. InExamples 1 and 2 the effect of the new burner is compared in theproduction of carbon black with that of the second type of known burnermentioned at the beginning of the specification.

In the examples Russoel II is a coal and petroleum distillate which is amixture consisting substantially of aromatic hydrocarbons boilingbetween 250 and 400 C.

EXAMPLE 1 Material Amount Russoel ll 25 kg/hour Atomizing air (5 atoms-7 Nm lhour pheres absolute) fuel gas (city gas with an upper 10 Nm lhourheating value of 4500 cal/Nm) Combustion air 96 Nm /hour The productionof carbon black amounted to 11.3 kilograms per hour which corresponds toa yield of 44.5 percent based on the Russoel II used. The testing of thecarbon black obtained showed the following results.

Carbon black properties Iodine surface area 99 rnlg DBP (dibutylphthalate) oil adsorption 1.35 ml/g Rubber technical test resultsModulus at 300 elongation 139 kg/cm Relative abrasion resistance 100EXAMPLE 2 For the production of a carbon black with reinforcingproperties on rubber there was employed a burner of the presentinvention in the form disclosed in the drawings with the followingreaction materials and quantities.

Material Amount Russoel ll 25 kg/hour Atornizing air (5 atmospheres 7 Nmlhcur absolute) Fuel gas (city gas with an upper l0 Nm lhour heatingvalue of 4500 cal/Nm) Combustion air Nmlhour 50.3 percent based on theadded russoel.

production of rubber blacks which are superior to the The production ofcarbon amounted to 12.6 kilograms per hour which corresponds to a .yieldof The testing of the carbon black obtained showed the following 5results.-

Carbon black properties iodine surface area 102 m lg DBP oil adsorption1.38 ml/g Rubber technical test results l0 Modulus at 300 kelongation145 kg/cm Relative abrasion resistance llO 7 (relating to the value ofExample l I 1 The burner of the invention therefore the EXAMPLE 3 Therewere used the following reaction materials and quantities MaterialAmount Russoel u 25 kg/hour Atomizing air (5 atmospheres I 16 Nm lhourabsolute Fuel gas (city gas with an upper 10 Nmlhour. 3 5

heat value of 4500 cal/Nrn) Combustion air 86.2 Nm /hour The productionof carbon black amounted to 14.2 kilograms per hour which corresponds toa yield of 40 56.5 percent based on the added russoel. The testing ofthe carbon black showed the following results.

Carbon black properties 103 mlg Iodine surface area Oil adsorption(dibutylphtalate) 1.6 ml/g Rubber technical test results Modulus at 300elongation I55 kg/cm Relative abrasion resistance 1 l8 (relating to thevalue of Example 1) As shown by a comparison with'Example 2 theproperties of the black prepared in Example 3 are even better ifincreased atomizing air is employed at the expense of combustion air.

In Examples 4 and 5 the effect of the new burner is compared in theproduction of carbon black with that of the second type of known burnermentioned at the beginning of the specification.

EXAMPLE 4 I For the production of a color black there was employed theknown burner of the prior art with the following reaction materials andquantities.

, Material Amount Russoel ll 25 kg/hour Carbon black propertiesAtomizing air (5 atmospheres 7 Nmlhour absolute) I Fuel gas (the same asin Example 1) l0 Nm 'lhour Combustion air Nmlhour KCl additive inaqueous solution 350 mg/kg russoel (The KCl was added as a 1 percent byweight aqueoussolution in Examples 4 and 5 r g The productionof thecarbon black amounted to 8.0 kilograms per hour which corresponds to ayield of 32.0 percent based on the addedrussoel. Thetesting of thecarbon black obtained showed the following results.

Iodine surface area 189 ml'g Oil demand (according to the. 262 vflowpoint method) 1 g Nigrometer scale 88' pH value I -9.l Volatileconstituents 3.4%

EXAMPLE 5 V For the production of a color black there was employed aburner of the present invention in the form disclosed in the drawingswith the following reaction materials and quantities. 1

Material Amount Russoel ll 25 kg/hour Atomizing air (5 atmospheres 7Nrnlhour absolute) Fuel gas (the same as in 10 Nm /hour Example 1)Combustion air 97 Nmlhour KCl additive in aqueous solution 350 mg/kgRussoel Carbon black properties lodine surface area 192 mlg Oil demand(according to the flow- 30$ point method) Nigrometer scale 83 pH value8.9 Volatile constituents 3.5

The burner of the invention therefore permits the production of colorblacks, which are superior to the color blacks, obtainable withconventional burner constructions in their properties and technicalapplications. Furthermore, the color blacks are obtained in higheryields.

The advantages obtained with the invention include:

1. Very fine distribution of the liquid in the gas is obtainable.

2. The apparatus is usable without essential changes in existing carbonblack production plants.

3. It is possible to produce furnace color blacks with higher specificsurface areas (greater than m /g) in good yields.

4. In the production of blacks for rubber reinforcement good yields,high structure and improved abrasion properties are obtained.

5. As the atomizing gas air can be used without draw back.

What is claimed is:

1. Apparatus for atomizing a liquid in a gas comprising a jacket pipehaving a constant cross-section over its major axial length which tapersat one end for conducting said gas, a nozzle having a cylindricalorifice connected to the tapered end of said jacket pipe and a feed pipehaving a constant cross-section over its major axial length enclosed andterminating with an internal taper within said jacket pipe adjacent saidone end thereof for conducting said liquid toward said tapered end 'ofsaid jacket pipe, the distance between the tapered, downstream ends ofsaid jacket pipe and said feed pipe in the axial direction being in therange of one tenth to ten times the inner diameter of said jacket pipewhereby said liquid is accelerated in the tapered end of said feed pipeand then is atomized in said gas when said gas is under goingacceleration due to the tapering of said jacket pipe and then themixture is increased in velocity due to said nozzle.

2. An apparatus according to claim 1 wherein said feed pipe is movablealong its longitudinal axis relative to said jacket pipe.

3. An apparatus according to claim 2 wherein said feed pipe ends in thetapered region of said jacket pipe.

4. An apparatus according to claim 1 wherein said feed pipe ends in thetapered region of said jacket pipe.

5. An apparatus according to claim 4 wherein said nozzle has a bore holethe open diameter of which is smaller than that of the jacket pipe.

6. An apparatus according to claim 5 wherein said nozzle has acylindrical bore.

7. An apparatus according to claim 5 wherein said I nozzle has aconverging-diverging shape.

1. Apparatus for atomizing a liquid in a gas comprising a jacket pipehaving a conStant cross-section over its major axial length which tapersat one end for conducting said gas, a nozzle having a cylindricalorifice connected to the tapered end of said jacket pipe and a feed pipehaving a constant cross-section over its major axial length enclosed andterminating with an internal taper within said jacket pipe adjacent saidone end thereof for conducting said liquid toward said tapered end ofsaid jacket pipe, the distance between the tapered, downstream ends ofsaid jacket pipe and said feed pipe in the axial direction being in therange of one tenth to ten times the inner diameter of said jacket pipewhereby said liquid is accelerated in the tapered end of said feed pipeand then is atomized in said gas when said gas is under goingacceleration due to the tapering of said jacket pipe and then themixture is increased in velocity due to said nozzle.
 2. An apparatusaccording to claim 1 wherein said feed pipe is movable along itslongitudinal axis relative to said jacket pipe.
 3. An apparatusaccording to claim 2 wherein said feed pipe ends in the tapered regionof said jacket pipe.
 4. An apparatus according to claim 1 wherein saidfeed pipe ends in the tapered region of said jacket pipe.
 5. Anapparatus according to claim 4 wherein said nozzle has a bore hole theopen diameter of which is smaller than that of the jacket pipe.
 6. Anapparatus according to claim 5 wherein said nozzle has a cylindricalbore.
 7. An apparatus according to claim 5 wherein said nozzle has aconverging-diverging shape.